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Ling Yue, Le Yu, Chao Xu, Yibo Lei, Yajun Liu, Chaoyuan Zhu
Newly developed global switching algorithm that does not require calculation of nonadiabatic coupling vector reduces computational cost significantly. However, there is a lack of extensive checking its accuracy for this simplest nonadiabatic molecular dynamic method in comparison with conventional Tully's fewest switches. It is very necessary to demonstrate how accurate global switching algorithm is. Extensive comparison between local and global switching on-the-fly trajectory surface hopping molecular dynamics is performed for cis-to-trans (800 sampling trajectories) and trans-to-cis (600 sampling trajectories) azobenzene photoisomerization at the OM2/MRCI level...
February 18, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Vladimir Petrovich Toshchevikov, Jaroslav M Ilnytskyi, Marina Grenzer Saphiannikova
Kinetics of photoisomerization and time evolution of ordering in azobenzene-containing materials are studied theoretically and by using computer simulations. Starting from kinetic equations of photoisomerization, we show that the influence of light is equivalent to the action of the effective potential which reorients chromophores perpendicularly to polarization direction. The strength of the potential is defined by optical and viscous characteristics of the material. The potential generates photomechanical stress of giant values ~GPa, in accordance with recent experimental findings for azobenzene materials deep in a glassy state...
February 17, 2017: Journal of Physical Chemistry Letters
Fangli Zhao, Lutz Grubert, Stefan Hecht, David Bléger
Azobenzene multi-state switches whose isomerization can be orthogonally induced with photons and electrons are presented. Exposure to green, blue, or ultraviolet light allows toggling between three isomers, while the fourth one is formed selectively via electrocatalytic isomerization.
February 17, 2017: Chemical Communications: Chem Comm
Lihong Liu, Yating Wang, Qiu Fang
Ethylene-bridged azobenzene (br-AB) has aroused broad interests due to its unique photoswitching properties. Numerous dynamical simulations have been performed for the br-AB photoisomerization, which focused mainly on the conformational effect and the funnel role of minimum-energy conical intersection (MECI) on the mechanism. In the present work, we use the "full quantum" ab initio multiple spawning method to simulate the br-AB photoisomerization, which provides new insights into the mechanism. Upon irradiation of br-AB to the first excited singlet state (S1), most of the excess energies are trapped in the azo-moiety...
February 14, 2017: Journal of Chemical Physics
Yangyang Yang, Ryu Tashiro, Yuki Suzuki, Tomoko Emura, Kumi Hidaka, Hiroshi Sugiyama, Masayuki Endo
Various DNA-based nanodevices have been developed on the nanometer scale using light as regulation input. However, the programmed controllability is still a major challenge for these artificial nanodevices. Herein, we demonstrate a rotary DNA nanostructure in which the rotations are controlled by light. A bar-shaped DNA rotor, fabricated as a stiff double-crossover molecule, was placed on the top of a rectangular DNA tile. The photoresponsive oligonucleotides modified with azobenzenes were employed as switching motifs to release/trap the rotor at specific angular position on DNA tile by switching photoirradiations between ultraviolet and visible light...
February 15, 2017: Chemistry: a European Journal
Mohamed Alaasar, Marko Prehm, Silvio Poppe, Carsten Tschierske
Organic ferroelectrics are of growing importance for multifunctional materials. Here we provide an understanding of the distinct stages of the development of sterically induced polar order in liquid crystalline (LC) soft matter. Three series of weakly bent molecules derived from 4-cyanoresorcinol as the bent core unit with laterally fluorinated azobenzene wings have been synthesized and the effects of the position of fluorine substitution, alkyl chain length and temperature on the LC self-assembly and polar order were studied...
February 13, 2017: Chemistry: a European Journal
Christopher R Opie, Naoya Kumagai, Masakatsu Shibasaki
A linear molecular architecture equipped with complementary three-fold hydrogen-bonding units embedded with a photoswitchable trans-tetrafluoroazobenzene moiety was synthesized. The transto cis photoisomerism of the azobenzene unit induced drastic changes in the molecular architecture as a result of intramolecular hydrogen bonding as evidenced by NMR spectroscopy and size exclusion chromatography. A minute stereogenic element in the linear trans state enabled stereoselective folding into the cis state, thus producing a globular architecture with enhanced chiroptical property...
February 14, 2017: Angewandte Chemie
Yui Suzuki, Ken H Nagai, Anatoly Zinchenko, Tsutomu Hamada
We have developed a novel system for photocontrol of the fusion of lipid vesicles through the use of a photosensitive surfactant containing an azobenzene moiety (AzoTAB). Real-time microscopic observations clarified a change in both the surface area and internal volume of vesicles during fusion. We also determined the optimal cholesterol concentrations and temperature for inducing fusion. The mechanism of fusion can be attributed to a change in membrane tension, which is caused by the solubilization of lipids through the isomerization of AzoTAB...
February 13, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Junwei Zhao, Zhaoshuai He, Biao Li, Tanyu Cheng, Guohua Liu
Recently, the controlled drug delivery system has become a potential platform for biomedical application. Herein, we developed a pH and light-dual controlled cargo release system exhibiting AND logic based on MCM-41 mesoporous silica nanoparticles, which was surface modified using β-cyclodextrin (β-CD) with imine bond and azobenzene derivative. The complex of β-CD and azobenzene derivative effectively blocked the cargo delivery in pH=7.0 phosphate buffered saline (PBS) solution without 365nm UV light irradiation...
April 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Hui Zou, Weizhong Yuan, Yeqiang Lu, Shanfeng Wang
UV light- and thermo-responsive supramolecular aggregates with tunable morphologies were obtained through the inclusion complexation between a β-CD containing dendritic host polymer and an azobenzene containing linear guest polymer. Morphologies of the aggregates could be adjusted by changing the molar ratio of host/guest polymers in the supramolecular polymers.
February 9, 2017: Chemical Communications: Chem Comm
Kyle M McElhinny, Peishen Huang, Yongho Joo, Catherine Kanimozhi, Arunee Lakkham, Kenji Sakurai, Paul G Evans, Padma Gopalan
The structural configuration of molecules assembled at organic-inorganic interfaces within electronic materials strongly influences the functional electronic and vibrational properties relevant to applications ranging from energy storage to photovoltaics. Controlling and characterizing the structural state of an interface and its evolution under external stimuli is crucial both for the fundamental understanding of the factors influenced by molecular structure and for the development of methods for material synthesis...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Youdong Shao, Zheng Guo, Hao Li, Yantao Su, Xinwei Wang
The atomic layer deposition (ALD) of iron sulfide (FeSx ) is reported for the first time. The deposition process employs bis(N,N'-di-tert-butylacetamidinato)iron(II) and H2 S as the reactants and produces fairly pure, smooth, and well-crystallized FeSx thin films following an ideal self-limiting ALD growth behavior. The FeSx films can be uniformly and conformally deposited into deep narrow trenches with aspect ratios as high as 10:1, which highlights the broad applicability of this ALD process for engineering the surface of complex 3D nanostructures in general...
February 7, 2017: Angewandte Chemie
Qiaofeng Yang, Ping Wang, Chuanzhuang Zhao, Wenqin Wang, Jingfa Yang, Qiao Liu
A self-healing hydrogel is prepared by crosslinking acrylamide with a host-guest macro-crosslinker assembled from poly(β-cyclodextrin) nanogel and azobenzeneacrylamide. The photoisomerizable azobenzene moiety can change its binding affinity with β-cyclodextrin, therefore the crosslinking density and rheology property of the hydrogel can be tuned with light stimulus. The hydrogel can repair its wound autonomously through the dynamic host-guest interaction. In addition, the wounded hydrogel will lose its ability of self-healing when exposed to ultraviolet light, and the self-healing behavior can be recovered upon the irradiation of visible light...
February 7, 2017: Macromolecular Rapid Communications
Sho Kaneko, Kouichi Asakura, Taisuke Banno
We demonstrate the phototactic behavior of self-propelled micrometer-sized oil droplets in the presence of azobenzene-containing surfactants. These droplets respond sensitively to UV light irradiation due to a variation in the interfacial tension at the droplet surface induced by the molecular conversion of the azobenzene-containing surfactants.
February 1, 2017: Chemical Communications: Chem Comm
V Ramakrishnan, Y Nabetani, D Yamamoto, T Shimada, H Tachibana, H Inoue
Nano-layered hybrid compounds composed of a polyfluoroalkyl azobenzene surfactant (abbreviated as C3F-Azo-C6H) and layered inorganic nanosheets undergo three-dimensional morphological changes such as reversible shrinkage and expansion of interlayer spaces, and nanosheet sliding by photo-irradiation. Previously, we have investigated the photoreactivity of C3F-Azo-C6H/clay nano-layered hybrids in various microenvironments and found a remarkable enhancement in the photoreactivity for the cis-trans photo-isomerization reaction (Φcis-trans = 1...
January 27, 2017: Physical Chemistry Chemical Physics: PCCP
Magdalena Staniszewska, Stephan Kupfer, Marta Łabuda, Julien Guthmuller
The ground state geometries and vibrational frequencies as well as the excitation energies and excited state gradients of the S1(nπ*) and S2(ππ*) states of trans- and cis-azobenzene are investigated by several DFT methods, namely B3LYP, PBE, M06-2X, CAM-B3LYP and ωB97X. Excited state properties and in particular gradients are also assessed using the wave function based methods EOM-CCSD and RASPT2/RASSCF. Comparison with experimental data shows that the B3LYP functional gives the most accurate results for the ground state geometry and vibrational frequencies...
January 24, 2017: Journal of Chemical Theory and Computation
Yayuan Li, Yawei Xu, Shubo Cao, Yongbin Zhao, Ting Qu, Tomokazu Iyoda, Aihua Chen
Nanoporous thin films with pore size of sub-10 nm are fabricated using an acid-cleavable block copolymer (BCP), a benzoic imine junction between poly(ethylene oxide) (PEO) and poly(methacrylate) (PMAAz) bearing an azobenzene side chain (denoted as PEO-bei-PMAAz) as the precursor. After a thermal annealing, the block copolymers are self-assembled to form highly ordered PEO cylinders within a PMAAz matrix normal to the film, even in the case of low BCP molecular weight due to the existing of the liquid crystalline (LC) azobenzene rigid segment...
January 24, 2017: Macromolecular Rapid Communications
N L Weineisen, C A Hommersom, J Voskuhl, S Sankaran, A M A Depauw, N Katsonis, P Jonkheijm, J J L M Cornelissen
Here we report on the covalent attachment of photoresponsive azobenzene moieties to cowpea chlorotic mottle virus (CCMV). The modified virus capsids can be reversibly immobilized on cucurbit[8]uril (CB[8]) bearing surfaces via supramolecular complexation.
January 24, 2017: Chemical Communications: Chem Comm
Nicolas Martin, Kamendra P Sharma, Robert L Harniman, Robert M Richardson, Ricky J Hutchings, Dominic Alibhai, Mei Li, Stephen Mann
Light-induced shape transformations represent a fundamental step towards the emergence of adaptive materials exhibiting photomechanical behaviours. Although a range of covalent azobenzene-based photoactive materials has been demonstrated, the use of dynamic photoisomerization in mesostructured soft solids involving non-covalent co-assembly has received little attention. Here we prepare discrete micrometre-sized hydrated particles of a hexagonally ordered polyelectrolyte-surfactant mesophase based on the electrostatically induced co-assembly of poly(sodium acrylate) (PAA) and trans-azobenzene trimethylammonium bromide (trans-azoTAB), and demonstrate unusual non-equilibrium substrate-mediated shape transformations to complex multipodal microarchitectures under continuous blue light...
January 23, 2017: Scientific Reports
Alexandre Mamane, Eloise Chevallier, Ludovic Olanier, François Lequeux, Cécile Monteux
Molecular interactions in thin liquid films, such as the disjoining pressure, are involved in interfacial phenomena such as emulsion and foam stabilization. In this article we show that through light stimulation we can control remotely the disjoining pressure in a thin liquid film stabilized by a photosurfactant. We stabilize a horizontal thin liquid film using a cationic photosurfactant, AzoTAB, bearing an azobenzene moiety on the hydrophobic tail which can switch from a trans to a cis conformation upon light stimulation...
January 23, 2017: Soft Matter
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